In one color system, an array or series of different color imaging stations are aligned above an endless belt. Each imaging station contains a raster output scanner (ROS), photoreceptor drum in a xerographic module, a development station, and cleaning station. The ROS emits an electronic beam (laser) which impinges on the rotating photoconductive drum, thereby causing that location on the drum to undergo a change in electrical charge. As the drum continues to rotate past the development station, toner particles of a color which is unique to that imaging station will attach to the drum at the location charged by the ROS. This colored image is then transferred to an intermediate transfer belt that is passing by, and in contact with the photoreceptor drum. As the intermediate belt passes by the different imaging stations (each containing a different color), it picks up subsequent color layers to create a complete color image which is then transferred to media.
Each colored beam must be in substantial registration with the other beams deposited on the belt for a proper final color copy. Also, each color station can be changed or varied when needed. In one embodiment, there are also two sensors (Mark On Belt, or MOB sensors) that are fixed in position to a point on the machine frame, such that the colored images pass within view of these sensors. These sensors serve to detect the quality of each color and can be used to indicate when a color change is required. Each color unit has its own motor so that it could independently be operated. This type of color system having an array of ROS units is generally described in U.S. Pat. No. 6,418,286 and is incorporated by reference into this disclosure.
As noted above, the color image deposited on the drum is subsequently deposited onto the belt. As the drum continues to rotate, it passes through the development station with a latent image which causes toner to stick to the drum where the electrical discharging (by the ROS) has taken place. The drum further rotates until the image is in contact with this intermediate transfer belt where the image is transferred from the drum to the belt. Each of the six or plurality of imaging stations deposits its own color and subsequently movement of the belt is moved past each of the imaging stations and allows each of the color separations to be deposited in turn. Thus, when the colors in the xerographic module are used up or should be changed, the xerographic module needs to be removed from the system.
As above noted, the MOB sensors will indicate when module servicing is required or when each color density, etc. needs to be changed to provide the optimum color images.
A key element of the present color systems is the ability to allow the customer to perform their own color station or module changeover. Each color station is designated for this customer interaction to all locations. Color changeover will be achieved by removing appropriate xerographic module from the xerographic marking system. The weight of the xerographic module is about 30-35 pounds which is relatively heavy and awkward to remove. To compound this challenge, the customer is required to attach the module onto slides while the module is held steady which can result in a safety hazard or realistically difficult task.